Wood boards or sheets, typically made from wood composite products like plywood or oriented strand board, are common construction materials in commercial, industrial and residential buildings. During construction, these boards are placed over and fastened to an underlying supporting frame to form the wall, roof or floor of the building. In order to improve the efficiency of fastening the boards to this frame, a pattern may be printed on the board or panel in order to rapidly attach the board to the frame structure.
Typically, ink is applied onto a board to form these patterns during the last stage of manufacture, shortly before the boards are packaged and readied for shipment. Most manufacturers perform this marking step at approximately the same speed as the speed at which the boards are inspected for defects so as to not interfere or impede board production. Unfortunately this high marking speed reduces the accuracy and intricacy of patterns that can be formed during marking, which may result in marking patterns that are simple or crude. While such markings might provide a minimally useful set of reference points, they do not maximize product versatility nor impart any special distinctiveness to the product.
One way to improve the marking process is to reduce the separation between the surface of the board and printheads of the printing system (commonly referred to as the xe2x80x9cthrow distancexe2x80x9d) that apply ink to the board (typically the printing system includes several print heads). When the throw distance is small, more accurate and intricate patterns may be formed on the board. However, such small separations between the surface of the board and the print heads also increases the possibility that during manufacture a board that is oversized, warped, misaligned or has a non-uniform thickness may accidentally contact the print heads and severely damage or destroy them. Because of this, a consistent gap must be maintained between the boards and the print heads. Furthermore, these variations of the board thickness and height can compromise the accuracy with which the ink is applied to desired locations on the boards thus, further deteriorating the quality of the patterns formed on the board surface.
Accordingly, there is a need for an apparatus to apply ink to the printing surface, wherein small separations between the boards and the ink application system can be used to enable intricate and accurate printing of complex patterns and designs at high production speeds. Furthermore, it is also desirable that the apparatus should have means for applying a normal force at several locations on the print surface to the boards to keep the printing surface of the boards in a flat, planar shape, the planar shape increases the accuracy of the locations that the inks are applied to the printing surface and thereby increases the quality of the patterns, marks, and ornamental designs formed on the printing surface of the boards.
What has been invented is an apparatus for applying ink patterns on boards, including: means for serially moving the boards in a selected direction and through a predetermined space; means for applying ink, said means for applying ink being movable from a first position adjacent the predetermined space to a second position remote from the predetermined space; and means for detecting boards moving in the selected direction and having a part thereof outside the predetermined space. The apparatus also includes: means responsive to the detecting means, for moving the means for applying ink from the first position to the second position when a board traveling in the selected direction is outside the predetermined space, whereby contact between moving boards and said means for applying ink is avoided; and means for controlling the means for applying ink to apply the ink patterns on the boards traveling within the predetermined space.
A feature of the invention is that the apparatus is capable of applying ink patterns on boards moving at rates of about 150 ft/min to 600 ft/min.
Another feature of the invention resides in that ink can be applied to boards at desired locations, as they move, with an accuracy of ∀0.125 inches.